on the basis of allele frequency distributions at 41 electrophoretic loci in the Atlantic cod. These authors reported a sig- nificant excess of rare alleles in populations of the Pa- cific cod, Gadus macrocqbhalus, but not in G. morhua. An important difference between the present study and that of GRANT and STAHL (1988) is the omission (by choice) of monomorphic RFLP loci. If expected num- bers of rare allozyme alleles are recalculated from 18 loci that exhibit polymorphism in Grant and Stahl’s study, a significant excess is observed (12 present with frequencies < 0.01 but only 6.7 expected), similar in magnitude to that in Mork et al.’s (1985) study. If Atlantic cod have experienced a recent expansion